It is estimated that throughout the world there are millions of people that suffer some degree of hearing impairment ranging from mild loss to total deafness. Such conditions are attributed to genetics, accident, disease and environmental conditions including work related.
In order to accommodate the deaf and significantly hearing impaired the motion picture industry has provided motion pictures with captioning which is the display of the audio text of the motion picture projected usually at the bottom of the screen.
Captioning has been well known in the motion picture industry and dates back to the days of silent movies and later the famous bouncing ball sing along shorts. Captioning is also utilized in connection with motion pictures to display a foreign language translation and to display various captions as part and parcel of a motion picture. While captions integral with the projected image work well for delivering the audio portion of a motion picture to those who are not able to hear it, there is a substantial reluctance of motion picture studios and exhibitors to provide captions on regularly distributed pictures. The primary reason is that it has been found that audiences without hearing impairment find such captions a distraction.
There have been a number of attempts to provide a caption of the audio portion of a motion picture that cannot be seen by the hearing audience and while some of them have provided this objective, they have not been commercially accepted for various reasons.
U.S. Pat. No. 4,859,994 to Zola utilizes polarized eyeglasses of the type used in stereographic (3D) projection systems where each eye views a different projected image, However, the device disclosed in Zola requires a 50 foot wide LCD (liquid crystal display) screen which would be financially prohibitive to many smaller theater owners. It also would require the theater to be refitted with a polarization preserving screen. U.S. Pat. No. 5,793,470 to Haseltine et. al. utilizes an LCD projector to project a polarization encoded image onto a polarization preserving screen and viewing it with polarized glasses. There are substantial problems in reducing this method to commercial practice since polarized filtered light has to be substantially brighter than ordinary projection levels due to the filtering.
The prior art also includes eyeglasses with individual text generators such as in U.S. Pat. Nos. 5,793,470 and 6,005,536 but at present such equipment would not be economical and the weight has found to be uncomfortable to many users. There have also been prismatic glasses where the caption would be projected on the ceiling or rear wall of the theater and viewed with a prism or mirror arrangement. These systems have not been well received since alignment is a problem and some viewers have experienced headaches and eyestrain.